Background & Aims: Development during childhood is vital for learning skills. Maternal omega-3fatty acids during pregnancy and lactation play important role in childhood development. The aim of this study is to determine omega-3 supplementation during lactation on the growth and development of infants.

Materials & Methods: This is a double-blind randomized trial. A total of 70 lactating women and their infants 15 days after delivery were selected. They were randomly divided into intervention and placebo groups. The intervention group received 1 gram omega-3 capsules daily and placebo group paraffin capsules for 3 months. Development of infants was assessed by using ASQ and growth by measuring weight, length and head circumference.

Results: The main score of communication, fine motor and problem solving in the intervention group after 3 months supplementation of omega-3 fatty acids were higher in the intervention group than placebo. There were no differences in gross motor and social development between two groups.

Conclusion: In this study positive effect of omega-3 e on problem solving and social development were found. There were no differences in growth between two groups except head circumference.